A mower for grass, weeds, leaves and the like (hereinafter referred to as clippings) has a rotating cutter blade on the underside of it. The clippings are conveyed via a chute by an air flow due to rotation of the cutter blade. The clippings are received in a collection bin or bag for collection and disposal. In the prior art, various bin or bag fullness detection systems have been utilized, however, each has shortcomings.
Some prior art systems utilize a sight glass. The sight glass requires the operator to look rearward while mowing or collecting material to examine the sight glass. In dim light the sight glass is not usable. The environment is very dirty, and the sight glass will haze over time rendering the sight glass useless or requiring the sight glass to be replaced. This is a non-direct visual indication only.
Other systems utilize mechanical switches, however, pressure activated switches or displacement activated switches do not offer adjustability for the material type that is being collected. Wet grass will trigger a pressure activated switch sooner than dry leaves causing the sensor to trigger prior to the material bin being filled completely or not triggering and resulting in a plugged chute. The adjustable pressure activated switch in U.S. Pat. No. 9,510,510B2 rectifies this issue but requires the operator to exit the vehicle to adjust the sensor. A sensor mounted on the floor of the bin is susceptible to damage.
Fill sensors that work on air pressure or flow indicate that the bin is full once the bin is filled to the point where air flow is restricted. This can lead to overfilling and plugging of the chute if immediate action is not taken. Mechanical indicators such as the type mounted on the chute require the operator to frequently look at the sensor to determine if the bin is full. Since the sensor works on air pressure it indicates that the bin is full once the bin is completely full. Continuing to collect material will result in over filling and/or plugging the chute. Another issue with this technology is that the sensor cannot be adjusted for the weight of the material which affects air flow and pressure.
There is a need for a sensor that is easily adjustable based on the material being collected to ensure the sensor triggers when the bin is full, not under filled or over filled.